In many conveying devices such as, for example, elevator installations, cranes or hoists use is made of belt-shaped support means. These support means generally comprise a plurality of tensile carriers which consist of steel wires and which accept the tensile forces to be absorbed by the support means. The tensile carriers are generally surrounded by a casing of synthetic material. The casing protects the tensile carriers from, for example, mechanical wear, since the support means are frequently guided around deflection points. In addition, the casing improves the traction of the support means on deflecting or drive rollers and fixes the arrangement of the tensile carriers relative to one another.
Such support means are a safety-relevant component within a conveying device. Failure or breakage thereof can lead to substantial harm to objects or persons. For this reason, use is made of check units in conveying devices, which check, in particular, the mechanical state of the tensile carriers. Damage of the tensile carriers accepting the forces shall thereby be able to be recognized in good time so that the support means in the case of damage can be exchanged in order to prevent failure of the conveying device.
The electrically conductive, metallic tensile carriers are surrounded by the electrically insulating casing of synthetic material. In order to carry out a check of the state of the tensile carriers contacting of a contact element with the tensile carriers is necessary in some methods. In one known method an electrical current, which serves as a test current for the purpose of ascertaining the state of the tensile carriers, is conducted through the tensile carriers with the help of the contact element.
DE 3 934 654 A1 shows a support means of the category described above. The ends of the tensile carriers are in that case conductively connected in pairs with a bridge member so that the tensile carriers of the support means are electrically connected in series. The tensile carriers of the support means are connected with a voltage source by way of an ammeter so that the state of the tensile carriers can be assessed by means of the test current which is conducted through all tensile carriers by virtue of the electrical connection in series.
WO 2005/094249 A2 shows a system for contacting a support means in which the contact elements puncture the casing of the support means perpendicularly to a longitudinal axis of the tensile carriers and then penetrate into the tensile carriers. It can be disadvantageous in that case that the contact elements due to the required puncturing process through the casing miss the tensile carriers. In addition, a transfer resistance between the tensile carriers and the contact elements penetrated therein can change over time which has a disadvantageous effect on the meaningfulness of a monitoring procedure.
WO 2010/057797 A1 and WO 2011/003791 A1 show systems for contacting a support means in which contact elements are mounted on exposed tensile carriers of the support means, for example by resilient contacts or by contact spikes penetrating into the tensile carriers. It is disadvantageous with such contacting systems that the connection between contact elements and tensile carriers is non-constant and that a high transfer resistance between the contact element and the tensile carriers is present.